You technically could do that... at least on a relatively short, flat, straight track... but it doesnt make any practical sense.

First, its a ram jet so something has to get it up to speed before the ram jet starts working. Though if we just make it a scramjet, there we go.

Next problem is ... it might actually need downforce winglets on it the way drag cars do. On every car. Hope there is no sudden cross wind on your nearly perfectly straight track in a large flat area. Now you need a computer system to automatically move the winglets to counter cross winds... or you need some kind of... train... pilot...???

Biggest problem is: The speeds capable by a theoretically working scramjet train would mean it could not turn on anything other than VERY wide arcs, and it wouldnt be able to get to the speeds capable of a scramjet... ostensibly the whole point... without skipping tons of stops a slower train could make...

...unless you are going to slow the thing down at each stop with a series of parachutes coming out the back, or some how be able to reverse thrust the scramjet?

As far as I know there are no reverse thrust scramjets, fairly sure thats impossible due to the nature of scramjets.

???

The project pluto express. Beijing to Brooklyn in, like, 5-6 minutes.